Turbine engines, and particularly gas or combustion turbine engines, are rotary engines that extract energy from a flow of combusted gases passing through the engine onto a multitude of turbine blades. Gas turbine engines have been used for land and nautical locomotion and power generation, but are most commonly used for aeronautical applications such as for aircraft, including helicopters. In aircraft, gas turbine engines are used for propulsion of the aircraft. In terrestrial applications, turbine engines are often used for power generation.
Gas turbine engines for aircraft are designed to operate at high temperatures to maximize engine efficiency, so cooling of certain engine components, such as the high pressure turbine and the low pressure turbine, can be necessary. Typically, cooling is accomplished by ducting cooler air from the high and/or low pressure compressors to the engine components that require cooling. Temperatures in the high pressure turbine are around 1000° C. to 2000° C. and the cooling air from the compressor is around 500° C. to 700° C. While the compressor air is a high temperature, it is cooler relative to the turbine air, and can be used to cool the turbine.
Cooling air used to cool the engine components is routed to the hot surfaces of the engine components through one or more film holes. Air exiting the film holes spreads across the hot surface of the engine component, cooling the engine component and creating a barrier between the hot air and the engine component surface. Typical film holes deliver cooling air along an engine component, which is subject to a high speed, turbulent hot air flow, where the cool air quickly mixes out with the hot air. As such, additional film holes can be necessary to maintain the cooling air barrier to properly cool the engine component, increasing cost, reducing structural integrity and component life, and reducing engine efficiency.